I deal with many businesses for Mini parts and other things around the world and have been going back to the 70's. Of these, there's many I have long term business relationships and some that I started back in the early 80's that endure to this day.
I've had a few dealings with Mini Sport going back to the 80's. Everytime I've been burnt and everytime I had given them another go, thinking that 'surely they must have changed' but alas, nothing but utter and bitter disappointment. In my last dealings with they, they were quite dishonest. To me, they no longer exist.
In regards to Mini Spares, well, it's like chalk and cheeze compared to the other lot. For one thing, what they say they have in stock, they actually do. The parts have usually been of a high quality and when there's been an issue, it's been no fuss what so ever to resolve. They are delightful to deal with and many other businesses (not just Mini Spares Parts) could learnt a lot from their model.